58 Pasture Problems 



year, although we have occasionally seen plants on a field even up to 

 the twelfth year. 



Anthyllis Vulneraria. Although a primary plant on some types 

 near the sea, is locally exotic to all the types under review. Sometimes 

 gives good results in the first hay crop on soils derived from Terannon 

 shales, but is not persistent and has only shown traces in the third year 

 (Table VI D). 



Medicago lupulina is a secondary plant on limestone soils in Pem- 

 brokeshire and North Wales, but is exotic on all the types here discussed. 

 It is largely sown in these districts, but above 600' is a complete failure, 

 seldom even contributing to the first year's hay ; below 600' it some- 

 times bulks satisfactorily in the first hay crop but does not appear to 

 last into the second year. 



Medicago saliva is an exotic plant which we have never seen succeed 

 in mixtures on any of our types ; on gravel it sometimes contributes 

 shghtly to the first year's hay crop. , 



Miscellaneous herbs. 



The competitive interaction of miscellaneous plants between them- 

 selves and with the grasses and clovers has been dealt with elsewhere 

 by one of us in so far as the first year is concerned^ and is still under 

 investigation with regard to the later years, consequently but few 

 species will be here discussed. 



Species which are frequently sown. 



Achillea Millefolium is probably a shght secondary plant on all 

 the types reviewed; but when unsown is usually late (about sixth or 

 seventh year) to come in naturally in appreciable amount (Table III). 

 Seeding would seem to hasten its appearance. 



Cichorium Intyhus is exotic on all the types, but sometimes makes 

 a sporadic appearance being a sown impurity with foreign red clovers. 

 From large seedings it often succeeds well on the soils derived from 

 Terannon shales and has shown itself able to persist until the third 

 year (Table VI D) and in traces until the fourth year. 



Poterium Sanguisorha. Exotic to our types and not a general 

 success when sown; but sometimes completely dominates the ground 

 on dry banks. 



1 See Stapledon (18). In this connection it will be necessary also to recognise Tertiary 

 Species, e.g. such as can thrive under grassland conditions for a few years and then com- 

 pletely disappear 



